Gas laser having a cylindrically-shaped discharge tube

Abstract

A gas laser havinng a cylindrically-shaped discharge tube in which at least one end is terminated with a metal end cap which supports a mirror body in its central area, supports a metal pump stem in a position eccentric to the longitudinal axis of the tube and supports a thermal compensation element in a position opposite and radially symmetrical to the pump stem whereby at gas laser operating temperatures, the compensation element deforms the metal end cap to substantially the same extent as the pump stem so that the influence of cap deformation on the mirror orientation relative to the longitudinal axis of the tube is minimized or at least approximately compensated.

What is claimed as new is as follows: 
     
       1. In a gas laser having a cylindrically-shaped discharge tube which has at least one end thereof terminated with a metal end cap which supports a mirror body in a central area of such cap and supports a metal pump stem in a position eccentric to a longitudinal axis of the tube, said mirror body being orientated along the longitudinal axis of said tube, the improvement comprising wherein: said metal end cap is provided with at least one thermal compensation element located at a select position of said end cap so that at gas laser operating temperatures, said compensation element deforms the end cap to a substantially identical extent as the pump stem so that the influence of end cap deformation on mirror orientation relative to the longitudinal axis of the tube is at least approximately compensated.   
     
     
       2. In a gas laser as defined in claim 1 wherein said thermal compensation element is located substantially radially symmetrical to and opposite said pump stem on said metal end cap. 
     
     
       3. In a gas laser as defined in claim 1 wherein said thermal compensation element and said pump stem are formed of an identical metal. 
     
     
       4. In a gas laser as defined in claim 3 wherein said discharge tube includes an envelope composed of glass, said end cap member is composed of an alloy selected from the group consisting of a Ni-Fe based alloy and a Ni-Fe-Co based alloy and said pump stem and thermal compensation element are composed of copper. 
     
     
       5. In a gas laser as defined in claim 1 wherein said pump stem and metal end cap are composed of an identical metal. 
     
     
       6. In a gas laser as defined in claim 1 wherein said discharge tube includes an envelope composed of glass and said end cap, said pump stem as well as said thermal compensation element are composed of an alloy selected from the group consisting of a Ni-Fe based alloy and a Ni-Fe-Co based alloy. 
     
     
       7. In a gas laser as defined in claim 1 wherein said thermal compensation element is of an essentially identical form to that of said pump stem. 
     
     
       8. In a gas laser as defined in claim 7 wherein said thermal compensation element comprises a capillary tube which is closed on a bottom side thereof. 
     
     
       9. In a gas laser as defined in claim 7 wherein said thermal compensation element is also a pump stem. 
     
     
       10. In a gas laser as defined in claim 1 wherein said thermal compensation element is defined by a depression on the outer surface of said metal cap, said depression being filled with a solder mass. 
     
     
       11. In a gas laser as defined in claim 1 wherein said metal end cap is connected to said pump stem via a transition portion. 
     
     
       12. In a gas laser as defined in claim 11 wherein at least said end cap and said transition portion are composed of an identical metal.